The monoclonal antibody 29A1.4 recognizes mouse NKp46, also known as CD335. CD335, a member of the natural cytotoxicity receptor (NCR) family, is a glycoprotein with 2 Ig-like domains and a short cytoplasmic tail. Expression of CD335 is uniquely found on NK cells (including immature NK cells, defined as DX5- CD3-, and thereby allowing discrimination between NKT cells and NK cells (NKp46+, CD3-). Furthermore, unlike many of the NK markers which also stain NKT cells, staining with 29A1.4 is not strain specific. Staining has been shown on C57Bl/6, SJL, CBA/CA and BALB/C strains. NKp46 has been shown to play a role in NK cell-mediated lysis of several tumor cells and pathogen-infected cell lines.

The 29A1.4 monoclonal antibody has been shown to activate NK cells in vitro. The 29A1.4 monoclonal antibody does not deplete NK cells in vivo.